The frontosquamosal arch in newts as a defence against predators

Abstract

The bony frontosquamosal arch, found in most newts, is suggested to function in lessening injury during attack by predators. The arch strengthens the skull, protects the retracted eyes, and correlates with postcranial defensive structures. Newts also have tetrodotoxin in the skin, and this is probably the ultimate factor in the evolutionary development and maintenance of the arch. Cranial strengthening in anurans with poisonous or distasteful skin probably serves a similar function.

Comparative Osteology of the Genus Pachytriton (Caudata: Salamandridae) from Southeastern China

“…In contrast, the granular skin of terrestrial and amphibious newts absorbs water more efficiently from the substrate through capillarity (Toledo and Jared, 1993). In true newts, the frontosquamosal arch may act as a defensive mechanism that adds strength to the skull and protects the retracted eyeball during encounters with predators (Naylor, 1978). This arch is attenuate or incomplete in P. brevipes and northeastern P. inexpectatus and relatively firm in P. archospotus and southwestern P. inexpectatus.…”

“…3 possess a complete, relatively firm frontosquamosal arch. Grooves and ridges may provide additional strength (Naylor, 1978). However, lack of contact between the two processes is occasionally observed and can occur on either side.…”

Adaptations to Terrestrial Environments

“…This refers to a complete bony arch over the eye from the frontal bone to the squamosal bone (Naylor, 1978).…”

“…This refers to the series of interlocking plates that cap the neural spines of the vertebrate (Naylor, 1978).…”

“…As far as is known, species exhibiting this suite of characters also have complete frontosquamosal arches and usually have expanded neural arches (Naylor, 1978).…”